6 MUSSELS OF CUMBERLAND EIVER AND TRIBUTARIES. 



COMPARISON WITH MAUMEE AND KANKAKEE RIVERS. 



Both the Maumee and Kankakee Rivers, which were examined by 

 the present authors, are situated in regions profoundly modified by 

 the great glacier. In their basins the ice mass first removed the 

 entire fauna and flora, and when it melted estabhshed new channels 

 by which the river was restocked. 



The Cumberland Valley presents an entirely different history. It 

 is situated in a region which is geologically very old and which has 

 not been much disturbed since its first upheaval, except by the ordi- 

 nary forces of weathering and erosion and the subsequent formation 

 of mountains. The Cumberland and Pine Mountains, as well as the 

 great Cumberland Plateau, are portions of the Appalachian system, 

 and the wrinklirg which formed them took place toward the close of 

 the Upper Silurian period. Originally very much liigher than at the 

 present day, they have gradually yielded to weatherirg and erosion, 

 but are otherwise unchaitged. The great glacier reached only a little 

 below the Ohio River, wliich is far to the north of the Cumberland 



VaUey. 



CHARACTERISTICS OF THE MUSSEL FAUNA. 



Consequently a primitive fauna and flora are to be looked for in 

 this valley, one that began with the very origin of the valley itself, 

 and has been gradually developii:ig ever since without any serious 

 disturbance; and in fact the best American authorities regard the 

 Alississippi VaUey as the original home of fresh-water mussels upon 

 this continent, the rest of the rivers, ponds, and streams having been 

 populated from this source. Some authorities even say that there is 

 evidence to show that this fauna developed first in the New World and 

 then spread to the Old World. However that may be, it is certain 

 that the Mississippi area has the greatest diversity of species and the 

 most magnificent shells to be found anywhere in the world. 



The Cumberland and Tennessee Valleys are among the very oldest 

 portions of the Mississippi region, and are commonly looked upon as 

 the center of this wonderful mussel fauna. Accordingly we should 

 expect to find in them a great diversity of species, some of which 

 would be found nowhere else, and that such is the case has been well 

 shown by many conchologists. Over 80 different forms of mussels 

 have been reported from the Cumberland River, and the present 

 examination has added 3 others. This is considerably more than 

 twice the number found in the Maumee or the Kankakee River 

 systems, and is a remarkably large representation compared with any 

 river of equal size. A few of these species have never been reported 

 from any other locahty, but the great majority are common to the 

 southern portion of the ^lississippi system. Such of these as were 

 found during the present examination are enumerated on pages 14 

 to 19. 



